Around the time Sheldon Wickersham published his Reference Book he also created a Quick Reference Guide which was pretty neat. It was fold up plastic laminated page that presented a Timeline for Randall Made Knives. He took the dates from already established information so I believe it was very accurate. Don't know if any are still available but it was handy to carry around.
The problem with this type of thing is when put in print, it becomes "fact". In this instance, not only is some of what is on there incorrect from the get go, but things have changed with more available information that has come to light since the publication. I suppose it could suffice in some instances as a very broad guideline.
So, to say it is "very accurate" is, well, inaccurate. There would need to be a corrrected and updated version to be "very accurate".